Amplifying Voices Webinars

Amplifying Voices Webinar Series

The ASLO Early Career Subcommittee is pleased to invite you to our webinar series, “Amplifying Voices: Early Career Researchers Making Waves in Aquatic Sciences.” This webinar series promotes the exciting work of early career aquatic scientists from underrepresented groups in our global community. The series features presentations from early-career researchers. In each session, the presenters share their work in 20-minute presentations followed by a moderated Q+A. The presentations are free to the public.

Webinars are presented each month and are recorded. The videos are uploaded to ASLO's YouTube channel and are freely available for viewing.

Webinars presented in 2023 are included here. For webinars presented in earlier years, please click on the links below.

2021 2022

2023 Webinars

Our next speaker:

November 30, 2023

Sandra Klemet-N'Guessan
PhD Candidate
Trent University

Tell me where you live and I'll tell you what you pee: animal-mediated elemental recycling across space, time, and animal functional traits

Presentation Abstract

Aquatic animals are a key component of streams and lakes biogeochemistry as these release nutrients and carbon via their excretion. Animal nutrient excretion may vary with animal taxonomic rank, trophic position and abiotic factors such as light and nutrient supply. Light and nutrient supply is modulated by dissolved organic matter (DOM) which may indirectly affect animal nutrient excretion. Contaminants could also affect animal nutrient excretion as these can impair animal physiology by altering animal metabolism and inducing stress. Further, the ecosystem size and structure, including community composition and biomass, can have a strong impact on the contribution of aquatic animals to the ecosystem nutrient pool. To address the complexity of these dynamics, we examined animal‐mediated elemental excretion and recycling in both stream and lake ecosystems across gradients of DOM concentration and composition, and under contaminant exposure. We sampled aquatic consumers from a range of trophic positions in Lake Erie during two seasons (Summer vs. Fall) and in naturally DOM-variable streams and lakes. We also investigated the effect of chronic exposure to silver nanoparticles (AgNPs) under environmentally relevant conditions on fish nutrient and silver (Ag) release. We found that animals can be a substantial nutrient contributor relative to other sources due to their high biomass and that their contribution changes with trophic position and season. We also detected nonlinear relationships between animal-mediated nutrient recycling and DOM concentration and composition which dampened with increasing ecological scale. Lastly, we report the first fish DOM excretion signature and Ag excretion rates under AgNPs exposure. Our results highlight the context-dependency and variability of animal-mediated elemental cycling and showcases that animals are important modifiers and conduits of elements in aquatic ecosystems.

January 26, 2023
View on YouTube

Speakers:

Dr. Carolinne Rosa de Carvalho
University of São Paulo, Brazil

Cyanobacteria in the multiverse of methane production at Brazilian soda lakes

Presentation Abstract

Oxic methane production (OMP) has been reported to be a significant contributor to methane emissions from oxic surface waters. Cyanobacteria are often correlated with methane accumulation and emission in freshwater, marine, and saline systems. Demethylation of organic compounds, photosynthesis-associated methane production, and chlorophyll reduction activity are some of the known mechanisms for OMP related to photosynthetic organisms. The Brazilian Pantanal is the world’s largest wetland system with approximately 600 shallow lakes, most of which are highly alkaline and saline extreme environments. We explored metagenomic and chemical data from the Pantanal soda lakes (three with cyanobacterial blooms, one oligotrophic turbid, and one oligotrophic crystalline lake) for five potential OMP pathways, using genetic markers. Our results show that there is a strong positive correlation of dissolved methane concentrations with the bloom events. Metagenomic data together with nutrient and methane concentrations suggest that the organic phosphorous demethylation pathway has the most potential to drive OMP in lakes with blooms. However, the bloom-forming Cyanobacteria do not contain the necessary genes to carry out this process. We examined two bloom-forming cyanobacterial cultures for their ability to produce methane under in vitro conditions. Our data demonstrate that both strains produce methane, with the rates being strongly dependent on light and circadian rhythm. Therefore, in addition to classical methanogenesis by Archaea in the soda lakes, multiple OMP mechanisms by Cyanobacteria and other organisms contribute as well to methane emissions.

Luís Henrique Bordin
PhD Student
Universidade Federal do Rio Grande (FURG), Brazil.

Aquatic ecosystem metabolism of the Patos Lagoon Estuary: a multiscale approach

Presentation Abstract

The aquatic metabolism of estuaries and coastal lagoon ecosystems is of great importance to carbon and nutrient cycling between the terrestrial and oceanic environments, subject to anthropic pressures. The methodological approaches generally used to study these are limited in space and time scales, therefore requiring the use of integrated methodologies (such as by discrete and operational oceanography and numerical modeling) to get more accurate results. This study has been conducted in the Patos Lagoon Estuary, Brazil, the largest choked lagoon of South America, and aims to i) estimate the ecosystem metabolic rates gross primary production and respiration, and ii) verify the relation between the meteoceanographic variability, physico-chemical parameters and metabolic rates. The first two approaches, i.e., that by in situ oxygen-based bottle experiments (limited in time and space), and that by data from a meteoceanographic buoy (that expands observations in time), have already been concluded. Both approaches revealed the dominance of net heterotrophic conditions for the Patos Lagoon Estuary channel-sites. This was attributed mainly to the high turbidity and depth, since the euphotic zone rarely reaches the bottom. Important drivers of the metabolic rates were the dissolved inorganic nitrogen nutrients and light availability, both modulated by the wind-induced inflow of marine salty-waters, and outflow of freshwaters. The third approach by ecological numerical modeling is in progress and intends to expand the estimates in time and space scales, providing an integrated view of the entire Patos Lagoon Estuary metabolic rates and the biogeochemical dynamics.

February 23, 2023
View on YouTube

Speakers:

Qing Zhan
PhD Candidate
The Netherlands Institute of Ecology

Assessment of impacts of nature-based and technological restoration measures on ES delivery of freshwater quarry lake

Presentation Abstract

Healthy freshwater ecosystems provide vital ecosystem services (ESs) to surrounding residents, while their capacity may be hampered due water quality deterioration and climate change. This study aims to quantitatively evaluate how our restoration measures influence the ESs delivery, and how climate change impacts their effectiveness. We built an ecosystem service module that includes eight services into a well-validated ecological model (PCLake+), and applied this model to a quarry lake. Scenario analyses, including how ESs delivery responds to a technological-based (phosphorus-P reduction) and nature-based solutions (wetland construction) for eutrophication control, were carried out. Our results demonstrate that both phosphorus reduction and wetland construction were able to improve the delivery of ESs including swimming, P retention, and macrophyte habitat, though the response is non-linear suggesting a threshold relationship. No significant impacts are found on birding and irrigation. Our results suggest that climate change will have an overall negative impact on ESs delivery, with the magnitude differing among the services. Some limitations of our approach to ES modelling were discussed. Nevertheless, our approach, by establishing a quantitative linkage between ES services and lake ecosystem states, is one of the first to allow for mechanistic understanding of the potential influence of eutrophication control measures. This further contributes to filling the gap that in most of the current ES modelling tools, the ecosystem processes are oversimplified.

Ana Cristina Vasquez Vargas
PhD Candidate
Tongji University /Latin American University of Science and Technology

Unusually heavy Cu isotope signatures of the Changjiang (Yangtze) River: The impact of chemical weathering and delivery to the oceans

Presentation Abstract

March 23, 2023
View on YouTube

Speakers:

Dr. Wubneh Belete Abebe
ADSWE and Bahir Dar University, Bahir dar, Ethiopia

Ecological status as the basis for the holistic environmental flow assessment of a tropical highland river in Ethiopia

Presentation Abstract

There is an increasing need globally to establish relationships among flow, ecology, and livelihoods to make informed decisions about environmental flows. This paper aimed to establish the ecological foundation for a holistic environmental flow assessment method in the Gumara River that flows into Lake Tana in Ethiopia and the Blue Nile River. First, the ecological conditions (fish, macro-invertebrate, riparian vegetation, and physicochemical) of the river system were characterized, followed by determining the hydrological condition and finally linking the ecological and hydrological components. The ecological data were collected at 30 sites along the Gumara River on March 2016 and 2020. River hydrology was estimated using the SWAT model and showed that the low flow decreased over time. Both physico-chemical and macroinvertebrate scores showed that water quality was moderate in most locations. The highest fish diversity index was in the lower reach at Wanzaye. Macroinvertebrate diversity was observed to decrease downstream. Both the fish and macroinvertebrate diversity indices were less than the expected maximum, being 3.29 and 4.5, respectively. The normalized difference vegetation index (NDVI) for 30 m and 60 m distances from the river bank decreased during the dry season (March–May). Hence, flow conditions, water quality, and land-use change substantially influenced the abundance and diversity of fish, vegetation, and macroinvertebrate species. The pressure on the ecology is expected to increase because the construction of the proposed dams is expected to alter the flow regime. Thus, as demand for human water consumption grows, measures are needed, including quantification of environmental flow requirements and regulating river water uses to conserve the ecological status of the Gumara River and Lake Tana sub-basin.

Ben Lukubye
PhD Candidate
Emory University, Atlanta, USA

Prokaryotic community composition and functionality of a worldwide unique lake: Issyk-Kul, Kyrgyzstan

Presentation Abstract

We use metagenomics to determine how environmental factors shape the taxonomic and functional diversity, and the role of the most prominent prokaryotes in major biogeochemical processes in a worldwide unique lake Issyk-Kul. The microbial community in Issyk-Kul formed three distinct depth clusters: surface communities (< 1 m), mainly driven by temperature and carbon dioxide, shallow (1-55 m) and deep (> 99 m) communities. Carbon fixation pathways were enriched in shallow MAGs. Thiosulfate oxidation via the SOX complex was more enriched at shallow clusters. Our results reveal a unique microbial community in Issyk Kul, which varies in diversity and biochemical functions with water depth.

April 27, 2023

Speakers:

Vanja Milovanović
PhD Candidate
University of Belgrade

Charophyte oospores and gyrogonites in recent sediments of small water bodies as taxonomic characters and indicators of revitalization potential

Presentation Abstract

River floodplains consist of valuable shallow ecosystems, but the intensity of numerous anthropogenic activities results in natural floodplain habitats being fragmented and degraded. Stoneworts, macroscopic algae, are important inhabitants of shallow ecosystems. They are primary producers, provide habitat and food for various organisms, enhance water clarity, store carbon and nutrients, and maintain stability of these fragile habitats. Their reproductive structures (oospores and gyrogonites) are trapped inside the sediment diaspore bank, offering potential eco-friendly solution for habitat restoration and native diversity revitalization. Morphology of oospores and gyrogonites is one of the characteristics that could be useful for distinguishing charophyte species, especially in cases when thalii characteristics are not visible or are ambiguous. Therefore, the main aims of my thesis are to (1) determine the presence and abundance of oospores and gyrogonites in the sediments of selected localities in the flood zones of the Danube, Karaš, and Nera river in Serbia, (2) establish the taxonomic significance and precision of morphological parameters of propagules and their potential in the identification of charophyte taxa and create a preliminary key for their identification within the study area, and (3) assess the viability of propagules and provide preliminary recommendations for the preservation and potential revitalization of charophyte habitats in the research area to preserve and restore native diversity. This is the first diaspore bank study in Serbia. It will result in the first identification key for oospores and gyrogonites not only for Serbia, but for whole Balkan Peninsula.

Amit Kumar
Assistant Professor
Sathyabama Institute of Science and Technology

Does acidification affect the health and nutritional value of tropical fleshy seaweeds?

Presentation Abstract

We know that seaweeds have immense ecological and economic value. Hence, it is important to understand how climate change stressors will affect them? Most studies on acidification, another outcome of increasing concentrations of atmospheric CO2, and seaweeds have analyzed only a few response variables, mainly photophysiology. Therefore, we examined in detail the response of some tropical fleshy seaweeds to acidification. We investigated response of two red seaweeds Gracilaria foliifera and G. debilis, to carbon dioxide-induced acidification of seawater (pH 7.7) in a controlled laboratory experiment over two weeks. As response variables, we measured growth, productivity, redox state, primary and secondary metabolites. In brief, the results showed that both species will have advantages under acidified condition as the growth rate and productivity increased. Acidification influences the nutritional values of algae as a general increase in the amino acids, and fatty acids were observed. Besides, we also found improved antimicrobial activities of acidified algal extracts against several bacterial and fungal food pathogens.

May 25, 2023

Speakers:

Oluwaseun Awolumate
Researcher
Institute of Ecology and Environmental Studies, Obafemi Awolowo University, Ile-Ife, Nigeria

Aquatic Macrophytes Diversity and Distribution, a case study of Ifewara Reservoir, Osun State, Nigeria

Presentation Abstract

This study determined the species composition, diversity, distribution, spatio-temporal variations and community structure of macrophyte community in Ifewara reservoir, Osun State, Nigeria. The first base-line study on the reservoir since its impoundment. The results of the study were important for future monitoring program of the reservoir and facilitate better management strategies in the face of pollution from surrounding utilization and global climate change. Samples were collected from ten stations established over the three main basins of the reservoir (upper-flow, middle and lower basins). At each sampling station, plant species were collected and identified following standard procedures at the Obafemi Awolowo University Ile-Ife Herbarium. A total of 22 macrophyte species belonging to 17 genera and 13 families were recorded. The most dominant family was Onagraceae, which comprised four species. About two-thirds (65.2%) of the macrophtyes were of emergent form, 30.4% as floating form, and 4.3% as submerged form. Azolla pinnata, Wolfia microscopica and Lemna minor were recorded only during the dry season. PCA and Cluster analysis revealed a high correlation between upper and lower basins. The highest mean occurrence of 45.3±6.4% was recorded in the upper basin of the reservoir. The study concluded that the macrophyte community of the Ifewara reservoir was fairly diverse and most species were widely distributed.

Roudaina Boukheloua
PhD Student
Institute of Hydrobiology Biology Centre Ceske Budejovice, Czech Republic

Amazing Protists and How to find them?

Presentation Abstract

Protists are unicellular eukaryotes that exhibit different modes of nutrition, they can be Phototrophic (algae), Heterotrophic, or even Mixotrophic. Thus, they are important contributors to the aquatic food web, and the main grazers of bacteria in aquatic environments. Although some protists can be identified using microscopy techniques, Heterotrophic nanoflagellates (HNF) are morphologically similar despite the immense phylogenetic diversity. For this reason, it is challenging to isolate and culture them based on their morphology. Metagenomics offers a culture-free alternative towards the recovery of genomes from the vast amounts of metagenomic sequence data that is becoming available and has been transformative for understanding prokaryotic diversity.

Efforts to recover eukaryotic protist genomes, which may be hundreds of times larger than prokaryotic genomes, have remained limited due absence of long time series datasets with sufficient sequencing depth. In effect, genomes of abundant protists in freshwater habitats remain largely unknown. Here we assembled and binned 1096 metagenomes from decade-long time series from four lakes (Stechlin, Grosse Fuchskuhle, Breiter Luzin, and Tiefwaren) and assessed the recovery of the largest set of eukaryotic metagenome-assembled genomes (MAGs) from freshwater lakes. Close examination of over 1000 putative eukaryotic MAGs indicated several types of contaminations, from prokaryotes, viruses, and even multiple, taxonomically distinct eukaryotes within these metagenomic bins. Using conservative filtration thresholds and manual curation, we recovered the largest number of protist genomes from freshwater lakes, namely, 280 taxonomically coherent, high-quality eukaryotic MAGs that ranged from 5-50 MB in size.

September 28, 2023

Speakers:

Dr. Maja Ilić
Postdoctoral Researcher
Swiss Federal Research Institute for Forest, Snow and Landscape WSL

The role of essential dietary fatty acids for the fitness and competition in herbivorous zooplankton

Presentation Abstract

In aquatic ecosystems, biodiversity loss on producer level is believed to have cascading effects on multiple trophic levels. In particular the phytoplankton-zooplankton interface is of high interest, as the phytoplankton content of dietary polyunsaturated fatty acids (PUFAs) was found to be crucial for the fitness of the herbivorous grazer Daphnia, which is not capable of de novo synthesis of such PUFAs. Essential PUFAs are thus assumed to be a functional phytoplankton trait that affects the trophic transfer efficiency and dynamics between the primary producers and consumers. However, fatty acid composition of phytoplankton was shown to be taxon-specific. Thus, I hypothesized that the composition of essential dietary fatty acids is directly related to the diversity of the phytoplankton community, and that alterations in PUFA availability will affect the intraspecific competition in Daphnia. To address these hypotheses, I performed a common garden experiment with diversity-manipulated natural phytoplankton community and naturally coexisting D. longispina genotypes with pronounced differences in their susceptibility to limitations by dietary PUFAs. My findings demonstrate that altered phytoplankton community composition results in an altered composition of dietary fatty acids, and that single PUFAs directly affect competitive interactions between naturally coexisting D. longispina genotypes. I thus show that essential PUFAs are a functional phytoplankton trait that affects the trophic transfer efficiency and dynamics between the primary producers and consumers in aquatic ecosystems.

Yash
PhD Researcher
Indian Institute of Science Education and Research Kolkata

Mangrove leaf litter dynamics in integrated mangrove aquaculture (IMA) ponds of Sundarbans – synergy between phenolic and nutrients pool for sustainable blue economy

Presentation Abstract

Coastal mangroves serve various ecological and socio-economic functions, including as a driver of the coastal blue economy in the Northern Indian Ocean; hence, they are crucial to achieving the United Nations Sustainable Development Goals (SDGs). Sundarbans, the world’s largest contiguous mangrove forest, a UNESCO World Heritage Site, and a RAMSAR site formed on the delta of Ganga-Brahmaputra-Meghna, faces the northeast coastal Bay of Bengal (BoB). This ecosystem is key to the sustenance of the blue economy in the Bay of Bengal, including BoB rim countries. The coastal Indian Sundarbans is intensively used for aquaculture practices, leading to continuous anthropogenic stressors, including the release of pollutants. Moreover, such aquaculture practices are considered to unsustainable and can cause irreversible damage to the health of coastal oceans. In the present study, the efficacy of mangrove vegetation planted along the boundaries of aquaculture ponds in Sundarbans (integrated mangrove aquaculture-IMA) has been evaluated by investigating the role of mangrove leaf-derived phenolic groups (tannic and gallic acids) that can contribute significantly to carbon and nitrogen pools leading to better coastal bioresources yield. The values of dissolved inorganic nitrogen (50-300µM), o-phosphate (0.5-10µM), reactive silicate (10-80 µM), dissolved organic carbon (37 mg/L – 80 mg/L) exhibited wide variation, indicating a strong influence of anthropogenic forcings in recent years, and that the breakdown of mangrove leaf litter favored the ecological stoichiometry. The observed higher concentration of tannic acid encountered during the studied period highlighted alteration in the nitrogen cycle and showed that tannic and gallic acids maintained water quality and may have ultimately led to improved yield of coastal bioresources in the IMA pond. The current study provides a new approach to nature-based solutions (NbS) and for improving the income of aquaculture practitioners through a sustainable blue economy.

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